|Effective Treatment Options For Trigeminal Neuralgia
Originally published Summer 2001
Trigeminal Neuralgia or Tic Douloureux is a disorder of the fifth cranial (trigeminal) nerve that causes episodes of intense, stabbing, electric shock-like pain in the areas of the face where the branches of the nerve are distributed - lips, eyes, nose, scalp, forehead, upper jaw, and lower jaw. The disorder most often affects one side of the face, but some patients experience pain at different times on both sides. Although trigeminal neuralgia is not a common disorder with an annual incidence of 4-6 in every 100,000 people, it is the most common form of neurologic facial pain in the geriatric population. Women also seem more likely to suffer from this condition.
Early in their disease course, patients tend to experience spontaneous remissions with pain-free intervals lasting weeks to months. Over time, painful episodes often become more frequent and remissions are fewer. Routine activities of daily living, such as brushing teeth, chewing, swallowing, or simply touching the skin of the face can bring on pain, causing patients to avoid these behaviors.
The diagnosis of trigeminal neuralgia is made almost exclusively on the patients history. Neurologic exam is normal in most patients. Although imaging studies are generally normal, patients with this disorder should have magnetic resonance imaging performed because of the small incidence of associated tumors and demyelinating disease.
Patients newly diagnosed with trigeminal neuralgia are typically treated medically. Tegretol has been the mainstay of medical treatment and approximately 70-80% of patients experience an initial therapeutic response to this medicine. The response rate to carbamazepine is typically so high that some clinicians will question the diagnosis if patients see no benefit. Up to 30% of patients will experience significant side effects related to initial therapy with carbamazepine including sedation, dizziness and nystagmus. Other medicines, including Neurontin, Elavil, Dilantin, and Baclofen have been used in the treatment of this disease with varying degrees of success.
Several authors have observed that the relief provided by Tegretol and other drugs tends to decrease over time. Additionally, medicine side effects often become more common in patients with persistent symptoms. It is estimated that up to 75% of patients fail to achieve long-term relief of their symptoms with medical therapy alone and about half of all patients with trigeminal neuralgia ultimately require an operation for pain relief. Surgical therapy for trigeminal neuralgia is reserved for cases that do not respond to medical management or when side effects of medicines become intolerable.
Three major forms of surgical therapy are presently indicated for patients with medically refactory trigeminal neuralgia. These include percutaneous attempts to destroy small portions of the trigeminal nerve, stereotactic radiosurgery and microvascular decompression of the fifth cranial nerve.
Percutaneous Techniques are well-tolerated outpatient procedures. Techniques used by Carolina Neurosurgery & Spine Associates for percutaneous rhizolysis (disruption) of the trigeminal nerve include injection of a drug (glycerol) into the trigeminal cistern or the use of heat energy (radiofrequency lesioning) in the area adjacent to the trigeminal ganglion. Both approaches result in the destruction of a small portion of the trigeminal nerve fibers and are associated with excellent initial responses, with 90-95% of patients experiencing relief of their pain. In large series, eight month pain-free rates are reported in the 60-70% range. The major downside of these minimally invasive procedures is that recurrence rates tend to be higher than with more invasive surgeries, such as microvascular decompression, and patients sometimes require repeat procedures. Because these procedures are inherently destructive, they are associated with a higher risk of sensory dysfunction. For these reasons, we generally reserve percutaneous techniques for patients with advanced age, poor medical condition or those who prefer a minimally invasive procedure.
Stereotactic Radiosurgery has recently been used to treat trigeminal neuralgia. The technique shows promise and some series have reported excellent response rates in the 80-90% range. Unfortunately, therapeutic responses may take weeks to occur in most patients. Additionally, there is very little follow-up with this technique compared to the other procedures. Because of this and because this also is a destructive procedure, physicians from our group have preferred to reserve this therapy for patients who are of advanced age or in poor medical condition. This technique may become a very important means of treating trigeminal neuralgia in the future.
Microvascular Decompression remains the gold standard by which all other procedures have been judged. Microvascular decompression involves a suboccipital craniotomy for exploration of the root entry zone of the fifth cranial nerve. Patients typically are hospitalized for a 2-3 day period. Despite the invasiveness of the procedure, microvascular decompression tends to be extremely well tolerated and very low morbidity rates have been reported in a variety of series, including our own. Sustained response rates in the 85 to 90% range are not uncommon with this procedure.
© 2001 Carolina Neurosurgery & Spine Associates